Properties of Retinal Synapses. The objective is to understand the mechanism of synaptic transmission in the vertebrate retina. Our approach is to record from retinal neurons in the isolated perfused skate retina. The perfused retina will allow quantitative studies to be carried out and hopefully will allow us to unravel the mechanisms of synaptic transmission in the retina. Furthermore, by systematically studying the retinas of marine fishes available in the Woods Hole area, we may be able to develop new preparations for visual physiologists. Mechanisms of Visual Excitation and Adaptation. The objective is to understand the mechanism by which a visual pigment molecule both excites and light-adapts a photoreceptor. Our approach is to quantitatively measure the extent to which excitation (i.e. light induced conductance change) and adaptation are localized to the region of photon absorption. The demonstration of localized excitation and adaptation in a photoreceptor indicates that the molecular changes which underlie these processes do not spread far from the site of photon absorption. Several agents, notably calcium ions, have been implicated as being involved in excitation and adaptation. Having demonstrated the extent to which excitation and adaptation are localized we will then be able to test the extent to which calcium and other agents act locally in effecting excitation and adaptation. In this manner it is hoped to gain some insight into the role these agents have in the process of excitation and adaptation.